Signaling system for telephone trunk-lines



(No Model.)

F. R. McBERTY.

SIGNALING SYSTEM FOR TELEPHONE TRUNK LINES.

No. 596,610. Patented Jan;4,1898.

I WIzesse-s: 22 4 2501".-

fimxrzmam I WWW fiMSfWM/hm z! UNITED STATES PATENT OFFICE.

FRANK R. MOEERTY, OF DOWN ERS GROVE, ILLINOIS, ASSIGNOR TO THE WESTERN ELECTRIC COMPANY, OF CHICAGO, ILLINOIS.

SIGNALING SYSTEM FOR TELEPHONE TRUNK-LINES.

SPECIFICATION forming part of Letters Patent No. 596,610, dated January 4, 1898. Application filed November 24, 1896. Serial No. 613,263. (No model.)

of a telephone-exchange for causing the act of removing a connection at one of the switchboards to display the signal at the other switchboard calling for a disconnection of the trunk-line at that switchboard also.

It is a matter of common practice in telephone-exchanges to unite telephone-lines terminating in sockets on difierent switchboards through the agency of a trunk-line extending between the switchboards and a pair of plugs and a plug-circuit at one of the switchboards, making connection'between the line there and the terminal of the trunk-line. In such systems it is usual to provide operators telephonic and signaling appliances in connection with the pair of plugs at one of the switchboards and to assign to the operator at that switchboard the work of supervising the connection, calling the required subscriber, ascertaining that connection has been completed, and effecting disconnection at the termination of conversation, the operator at the other switchboard merely obeying instructions from the supervising operator given orally or through the medium of signals.

In a prior application filed September 25,

1896, SerialNo. 606,495,'(Oase No. 43,) I have described a broadly new arrangement of signaling-circuits whereby the removal of one of the plugs of the pair from the spring-jack of the connected line by the supervising operator and the return of the plug to its normal idle condition causes the display of a clearing-out signal before the other operator, instructing her to disconnect the trunk-line from the correspondent subscribers line.

The present invention is a form of the general invention designed to simplify the cirthe self-restoring type.

cuits and apparatus and to secure certainty of operation in the system.

The present invention consists generally-in a signal-circuit which is normally closed, a signal-controlling instrument designed to display a clearing-out signal when inert in the circuit, and mechanism to break the circuit in the supervising operators act of withdrawing a plug of the pair from the spring-jack of the subscribers line, which is connected with another through the agency of the plugs and the trunk-line. Specifically it comprises a signal-circuit which during a connection through the trunk-line is complete from the subscribers spring-jack through a pair of plugs and a conductor uniting them and the signaling-circuit associated with the trunkline, means for maintaining the continuity of the circuit when the connecting-plug is withdrawn from the terminal spring-jack of the trunk-line, a signal-controlling electromagnet, and means for causing the signal of the magnet to become and to remain displayed when the magnet becomes inert. This circuit can then be broken only by the withdrawal of the proper plug of the pair from the spring-jack of the subscribers line, and when so withdrawn it causes the display of the clearing-out signal before the operator having charge of the distant terminal of the trunkline. I

The invention embodies also certain details involved in the operation of the system.

This device is shown in the attached drawing.

The diagram represents two telephone-lines 1 2 from substations A and A, extending to spring-jacks b in two switchboards B and B and connected with line-annunciators c in the switchboards. The annunciator used is of Its restoringmagnet is included in a local circuit 3, which is normally broken at separated contact-pieces d and cl in the spring-jack, which are designed to become crossed together through the sleeve of a plug inserted in the spring-jack. The trunk-line 4 5 extends between the switchboards B and B, terminating in a spring-jack e at switchboard B and in a plug f at switchboard B. Switchboard B is furnished with a pair of plugs g and g, which are united by conductors 6 '7, constituting the plug-circuit. With this plug-circuit are associated the usual calling-key 7t, listening key 'Z, and clear-.

connection is supposed to originate with thesubscriber at station A, the process of I making connection between the lines being effected as follows: The operator at switchboard B answers the calland makes connection between spring-jack b of the calling-line and spring-jack e of the trunk-line by means 3 of plugs g and g, inserted into them, respectively, and instructs the operator at switchboard B to insert the terminal plug f of the trunk-line into the line spring-jack b of the line called for. The operator at switchboard B then rings by means of her calling-key h, ascertaining by means of her telephone that the subscribers have entered into communication. The same operator, who is termed in practice the supervising operator, observes the signal for disconnection given by the clearing-out annunciator 7c and removes the plugs g and g from the spring-jacks. The invention is designed to cause the act of removing plug 9 from the spring-jack b to effect the display of the clearing-out signal before the operator at switchboard B to instruct her to disconnect the trunk-line from the line of the called subscriber. To this end a conductor 9 is associated with the trunk-line, terminating in arin g e in the spring-jack of the trunkline and including the magnet Z of the signalcontrolling relayat the switchboard B. The circuit from magnet Z is normally completed to earth through switch-contacts of a plugseat switch m in the normal resting-socket of plug f, being closed through the pressure of the plug in its socket. The relay is provided with an armature-lever Z, which plays between two switch-contacts Z and Z The 1ever Z is connected to earth. The forward contact Z is connected with the conductor- 9. The contact Z forms the terminal of a local branch 10, which includes a clearing-out signal n, (a small lamp,) together with a battery 0. The spring-jack e is provided, in addition to the line-contacts and the ring e, with a switch-spring e and its anvil 6 upon which the spring closes when no plug is in the springjack. The anvil e forms the terminal of a wire 11, led to a grounded battery 19.

The plugs g and g are provided with the usual contact sleeves or shanks q, these being adapted to register with the contacts d and d of the spring-jack b and with the thimble 6 of spring-jack e, respectively. The contacts, q of the two plugs arev united by a wire 12. The free pole of battery 19 is connected with circuit 3 at any convenient point, preferably in such a way that a direct connection with the wire 12 is effected when the spring-jack e.

plug g is inserted in thespring-jack b. In the idle condition of these appliances the circuit from battery 19 iscomplete through wire 11, switch-contacts e and e ,wire 9,and thence to earth either through the switch-contacts of the plug-seat switch m or through the contact Z Z of the relay, the relay being excited by the current flowing. The relay should of course have a high resistance in order that the operation may be efiected with a minimum strength of current.

'The operation of the signaling-circuit is as follows? Answering the call from the station A, the operator atswitchboard B first inserts plug 9 into the spring-jack b and their places plug 9' in the spring-jack 6, having learned thesubscribers order. Theinsertion of plug 9 into thespring-jack b completes a-circuit from battery 10 to conductor 12. The insertion of the plug g into spring-jack e separates the spring 6 from the anvil e and hence cuts off the wire 11 from the signaling-circuit, but at the same time brings the wire 12 into connection with wire 9, so that the signaling-circuit is not interrupted and the relay remains still excited. When the operator at switclr board B inserts the plug fin the spring-jack of the'line called for, the ground branch controlled by the plug-seat switch mis broken,but that controlled by the relay remains complete. Having received the signal for disconnection, the supervising operator first removes plug 9 from spring-jack b and later plug g from The first act breaks the connection between wire 12 and battery 19, interrupting the signaling-circuit and permitting relay Z to become inert. The armature of this instrument then falls back and closes a local circuit through wire 10, leading to the clearing-out-signal lamp n, as a signal to the operator at switchboard B to disconnect the trunk-line from the subscribers line. The withdrawal of plug g from spring-jack e and the replacement of plug fin its socket return the circuits to their normal conditions and cause the extinction of lamp n.

It will be observed that if at any time durin g the connection plug g should be removed from the spring-jack e the clearing-out signal would not be displayed, since the same act would eifect the connection of conductors 9 and 11. I

In the process of withdrawing the plugs g and g from the spring-jacks the first must be invariably withdrawn from the spring-jack of the calling-line in order to display the clearing-out signal.

This form of signaling-circuit has in practice several advantages, among which the chief is a saving in apparatus over the systems which have been commonly in use.

I claim as my invention 1. The combination with a subscribers line terminating in a spring-jack, a trunk-line and a plug connected with the trunk-line and adapted for insertion into the spring-jack, of a signaling-circuit including a clearing-out IIO signal at the distant terminal of the trunkline, said signal being adapted to be displayed when its controlling-magnet is inert, the signaling-circuit being completed through registering contact-pieces of the subscribers spring-jack and the plug therein, and a source of current permanently connected with the signaling-circuit to excite the said signal-controlling magnet whereby the withdrawal of the plug from the spring-jack causes the display of the clearing-out signal, as described,

2. The combination with a subscribers line terminating in a spring-jack, a trunk-line also terminating in a spring-jack, and a pair of plugs and a plug-circuit for uniting the spring jacks, of a signaling-circuit associated with and a trunk-line, said lines terminating inspring-jacks, a pair of plugs for uniting the spring-jacks, and a clearing-out annunciator connected with the plug-circuit thereof, of a signaling-circuit associated with the trunkline and completed through registering contact-pieces of each of the springjacks and the plug therein, and a conductor uniting the con-' tact-pieces of the plugs, switch-contacts in the trunk-line spring-jack adapted to close the signaling-circuit normally independently of the said registering contacts, a magnet in the signaling-circuit, and aclearing-out signal controlled thereby adapted to be displayed when the magnet becomes inert,whereby the withdrawal of the plug from the spring-jack of the subscribers line operates the signal for disconnection, as described.

4. The combination with a telephone-line and a trunk-line, said lines terminating in spring-jacks in a switchboard, a pair of plugs and their plug-circuit for uniting the springjacks, and a clearing-out annun ciator connected with the plug-circuit, of a signalingcircuit associated with the trunk-line completed through registering contacts of-each spring-jack and the plug therein, and a conductor uniting the contacts of the plugs, a

relay-magnet in the signaling-circuit, switchcontacts of the relay adapted to interrupt the signal-circuit whenthe relay is inert, a switch associated with the terminal appliance of the trunk-line and adapted to bridge the break at the relay when the trunk-line is not in use, a subsidiary clearing-out signal and a circuit including the signal closed by the relay when inert, substantially as described.

5. The combination with a subscribers line and a trunk-line, each of said lines terminating in a spring-jack, said trunk-line terminatin g in a plug'at another switchboard, a pair of plugs uniting'the lines, and a clearing-out ann unciator in connection with the plug-circuit thereof, of a signal-circuit associated with the trunk-line completed through registering contacts in eachof the spring-jacks and the plug therein, and a conductor uniting the contacts of the plugs, a switch in the trunkline s'p'ringjack adapted to complete the signal-circuit and constructed to be opened by the insertion of a plug in the spring-jack, a signal-controlling relay in the signal-circuit, said signal being located at the distant'terminal of the trunk-line, the switch-contacts of said relay being adapted to control the signaling-circuit, a plug-seat switch for the terminal plug of the trunk-line, and switchcontacts closed thereby connected to bridge the break of the signal-circuit at the relay, substantially as described.

6. The combination with a subscribers line provided with a self-restoring calling-annunciator' and a local circuit terminating in normally-separated contact-pieces in the springjack, of a trunk-line terminating in a springjack, and a clearing-out signal associated therewith, plugs for uniting the spring-jack of the line with that of the trunk-line, a clearing-out-signal circuit associated with the trunk-line and including an electromagnet controlling the'clearing-out signal at the distant terminal station thereof, said signalingcircuit being formed in part of the local rest0ring-circuit,a contact thereof inthe springjack, and a contact of the plug registering therewith, and a source of signal-current permanently connected with the signal-circuit to operate the signal therein, substantially as described.

In witness whereof I hereunto subscribe my name this 16th day of October, A. D. 1896.

- FRANK R. MCBERTY.

Witnesses:

ELLA EDLER, LUcILE RUSSELL. 

